1. Field of the Invention.
The present invention relates to a partial insole placed in the forepart of a shoe, to provide an excavation beneath the most frequently symptomatic site of the ball of the foot, the second metatarsal joint, thus relieving it of ground-reactive force, to reduce pain.
2. Description of Related Art Including Information Disclosed Under 37 CFR .sctn..sctn. 1.97 AND 1.98.
Various means have been used in attempts to relieve a frequent site of pain, at the ball of the foot. Having been a practicing and teaching podiatrist for twenty years I have become extremely familiar with the particular problem for which this invention is directed. Of the 100 patients I see per week, easily 20 will have had this problem. The problem has traditionally been referred to as "metatarsalgia" (meaning "pain at the ball of the foot") in the medical profession. In the dance and gymnastic communities it is called a "stone bruise" because it feels like the ball of the foot has focally and violently been embarrassed by a stone. Recent orthopedic literature has provided in-depth analysis of the condition. The condition is so common because many commonly-seen factors can cause it: such as bunions, hammer toes, weak toes, diabetes, high-arched feet, "Morton's" feet (those with long second metatarsals, the most common foot type of all), wearing high-heeled shoes, wearing thin-soled shoes, the inevitable thinning of the fat pad in the sole of the foot which occurs with age, flat feet, hypermobile ligaments, splay feet, overuse injuries from sports such as running, basketball, tennis, squash, aerobics, ballet, gymnastics, and cross-country skiing, and macro-traumatic events such as turf toe, joint dislocations, among others.
The single unifying factor in each of these circumstances is that it very well might focus inordinate ground-reactive force to the second joint at the ball of the foot, the second metatarsophalangeal joint. As this force continues, the ligament beneath the joint, called its "plantar plate", which is the entity most responsible for the stability of this joint, begins to thin out. In time the plantar plate micro-perforates and the second toe, having lost the entity responsible for its downward stability, loses its ability to "purchase" or competently grip the ground during stride. Thus, push-off forces are even further concentrated at the second ball joint, and pain ensues as the heel lifts during gait and weight transfers forward to the ball.
Of the 20,000 patients I've treated for this problem, 95% have tried some type of treatment before visiting me. The treatments they tried encompassed activity modification, such as cessation of pain-producing sports, or vastly-reduced amounts of walking, or limping, these are unsatisfactory because they compromise the normal lifestyle. Patients also tried shoe modification, such as reducing heel-height, wearing soft-soled shoes, or limiting themselves to the one or two pairs of shoes in their wardrobe which hurt the least; these strategies are not easily accepted due to societal requirements for wardrobe for business/dress, to psychological reasons (depression, self-esteem lowered), or for practical reasons (extreme difficulty and expense in finding satisfactory shoes or wasting money on unsatisfactory ones). Patients also tried over-the counter devices, such as padded inner soles, which deteriorate, take up a lot of room as often several layers are required for satisfactory effect, and do not specifically unweight the pain site, moleskin (adhesive pads taped to the pain site), which increases ground reaction and thus pain to the site, as do gel pads, or metatarsal pads (triangular, squat domes affixed within the shoe behind the pain site, towards the arch, which lose their functionality as soon as the heel elevates (the very moment when the pain site receives the greatest ground reaction is thus least protected with a metatarsal pad); to professional help, which can range from toe strengthening exercises (which often fail until the ball is protected because the patient refuses to stride into the toes if the ball is unprotected), to orthoses ($300-500 per pair lab-made custom in-shoe devices) with metatarsal pads affixed which don't frequently work due to the above mentioned rationale re met pads, to orthoses encompassing "pontoons", or thickening in the material of the orthosis in the forepart of the shoe which is precisely astride the pain site, thus enabling both a cavity beneath the pain site, reducing ground reaction there, as well as increasing ground reaction to the uninvolved metatarsophalangeal joints. In my experience this latter treatment, though expensive, time consuming and requiring both a doctor's visit as well as the awareness that one should visit (the right) doctor has a success rate well into the 90th percentile.